The team used surveys covering more than 180,000 children aged 4 to 17 between 1997 and 2016. The surveys were in-person with a parent or guardian and asked whether the child had ever been diagnosed with ADHD.

“Over the 20-year period from 1997 to 2016, we found a significant increase in the prevalence of diagnosed ADHD from 1997-1998 to 2015-2016,” they wrote in the Journal of the American Medical Association’s JAMA Open Network.